Production of tetramethyl suberic acid

ABSTRACT

2,2,7,7-TETRAMETHYL SUBERIC ACID IS MADE BY REACTING 2,7DIMETHYLOCTENE-4 WITH CARBON MONOXIDE IN STRONG SULPHURIC ACID, SEPARATING 2,2,7-TRIMETHYLOCATONIC ACID, FEEDING THE 2,2,7-TRIMETHYLOCTANOIC ACID TO A REARRANGEMENT REACTION WITH STRONG SULPHURIC ACID TO GIVE 2,2,7,-TETRAMETHYL SUBERIC ACID, FEEDING THE REARRANGEMENT PRODUCT IN STRONG SULPHURIC ACID TO THE CARBONYLATION ZONE, AND RECOVERING 2,2,7,7-TETRAMETHYL SUBERIC ACID FROM THE CARBONYLATION PRODUCT.

Unitcd States Patent US. Cl. 260-533 A 13 Claims ABSCT OF THE DISCLOSURE 2,2,7,7-tetramethyl suberic acid is made by reacting 2,7- dimethyloctene-4 with carbon monoxide in strong sulphuric acid, separating 2,2,7-trimethyloctanoic acid, feeding the 2,2,7-trimethyloctanoic acid to a rearrangement reaction with strong sulphuric acid to give 2,2,7,7-tetramethyl suberic acid, feeding the rearrangement product in strong sulphuric acid to the carbonylation zone, and recovering 2,2,7,7-tetramethyl suberic acid from the carbonylation product.

The present invention relates to the production of 2,2, 7,7-tetra-methy1 suberic acid.

, It is known from Belgian Pat. 735,340 that 2,2,7,7- tetramethyl suberic acid (TMS) may be made by reacting 2,7dimethyl octene-4 (DMO) with carbon monoxide and water in the presence of a strong acid catalyst, for example concentrated sulphuric acid. 2,2,7-Trimethyl octanoic acid (TMO) is also produced. The TMS and TMO can be separately isolated from the strong acid reaction mixture by diluting this with water in two stages, and the TMO can be converted to additional TMS, by reaction with additional concentrated sulphuric acid, where it undergoes re-arrangement to TMS as described in B.P. 1,270,939. Both steps of this process require large amounts of sulphuric acid, for instance 0.5 to 6 volumes per volume of olefin feed, of a concentration which is preferably not less than 95% by weight and is most preferably between 97% and 100% by weight. Although the diluted sulphuric acid, which results from the isolation of the products after both steps of the process, can be reconcentrated, this is an expensive process and the cost of providing the concentrated sulphuric acid forms a substantial part of the total costs of this process.

It has been found that a substantial economy, in the amounts of concentrated sulphuric acid used, can be achieved by continuously feeding part or all of the rearrangement reaction product as catalyst to the carbonylation reaction.

According to the present invention the process for the production of 2,2,7,7-tetramethyl suberic acid comprises continuously feeding 2,7-dimethyl octene-4, carbon monoxide, and aqueous sulphuric acid having a concentration in the range 90 to 97% by weight to a carbonylation reaction zone to produce 2,2,7-trimethyl octanoic acid, continuously separating the 2,2,7-trimethyl octanoic acid from the carbonylation reaction product, feeding 2,2,7- trimethyl octanoic acid into contact with sulphuric acid having a concentration in the range 94% to 99.5% by weight in a re-arrangement reaction to product 2,2,7,7- tetramethyl suberic acid, continuously feeding to the carbonylation reaction zone as part or all of the sulphuric acid feed at least part of the re-arrangement reaction product containing 2,2,7,7-tetramethyl suberic acid and concentrated sulphuric acid concentration in the range 90% to 97% by weight, and recovering 2,2,7,7-tetramethyl suberic acid from the carbonylation reaction product.

3,776,951 Patented Dec. 4, 1973 OLEFIN FEEDSTOCK Although it is possible to introduce fresh sulphuric acid catalyst into the carbonylation reaction, in practice it is preferred that the whole of the acid catalyst for the carbonylation reaction is provided by recycling part or all of the re-arrangement reaction product, if necessary after dilution with water to give a sulphuric acid concentration in the range to 97% by weight. This may be carried out by adding water to the re-arrangement reaction product or separately to the carbonylation reaction mixture to give the desired acid concentration. Preferably the sulphuric acid concentration is between 90% and by weight.

The reaction of the DMO and carbon monoxide may be carried out over a moderately wide range of temperatures for example from 0 to 100 0, preferably from 15 to 35 C.

The carbonylation reaction may for example be carried out with total pressures in the range 1 to 200 atmospheres but it is preferred to use pressures of 10 to 100 atmospheres.

The residence time in the carbonylation reaction may vary over a moderately wide range. Examples of suitable times are those in the range 1 to 12 hours, preferably from 2 to 6 hours.

The carbonylation reaction may be carried out in any convenient form of apparatus which enables adequate contact between the reactants to be obtained. Suitably the reaction is carried out in a stirred tank reactor capable of operating at increased pressures to which reactants are fed, and products removed, continuously, or in a plurality of such reactors with the product from one reactor being fed into another for reaction with further quantities of carbon monoxide and/ or olefins.

RECOVERY OF REACTION PRODUCTS The TMO and TMS are continuously separated from the carbonylation reaction product in any suitable manner. In one method sufficient water is added to the reaction product to dilute the sulphuric acid to a concentration of about 60% by weight, which causes both the TMO and the TMS to form a separate liquid phase which can then be decanted from the acid phase. The TMS may then separate by crystallisation from the TMO and it can then be isolated by filtration. The T Ms isolated in this manner 9 is contaminated with TMO which may then be separated more completely be re-crystallisation, as disclosed in British Pat. 1,276,642. In this method the mixture of TMO and TMS is dissolved in a carboxylic acid solvent such as acetic acid, TMS being obtained on re-crystallisation. A preferred method of separating the two product acids, described in Belgian Pat. 766,429 and US. Pat. application Ser. No. 136,609 filed Apr. 22, 1971, is to add only sutficient water to cause the TMO to form a separate liquid phase, e.g. to dilute the sulphuric acid to a concentration of about 90% by weight. The TMO phase is decanted and a further quantity of water is then added to the partially diluted strong acid phase to dilute the sulphuric acid to a concentration of below 80% by weight, preferably about 60% by weight, at' which concentration the TMS forms a separate phase which is decanted.

RE-ARRANGEMENT REACTION The TMO separated from the carbonylation reaction product is converted to TMS in a re-arrangement reaction by bringing it into contact with fresh sulphuric acid of a concentration of 94% to 99.5% by weight, preferably from 97% to 99% by weight. The amounts of sulphun'c acid can vary over a moderately wide range for example from 5 to 20 moles per mole of TMO preferably the other half was worked up in the following manner. The mixture was diluted with water (to give aqueous 90% by weight H 80 and the liberated TMO phase was decanted before diluting further to 67% w./w. H 80 to precipitate the TMS. The unconverted TMO (5.9%) was from 8 to 18 moles per mole TMO. 5 recycled to the next rearrangement step. The TMS was The re-arrangement reaction can be carried out at temseparated from the catalyst raffinate by filtration and was peratures from l5 to 80 C., but it is preferred to opwater washed on the filter bed. After drying the TMS oberate at temperatures of from l5 to 40 C. Temperatained corresponded to 100% selectivity on the TMO tures over 80 C. should be avoided as oXidative side re- 10 consumed. action may occur. A portion of the H 50 rafiinate'(l.13 mole) from the The reaction pressure is not critical, and it is convenrearrangement step was rotary evaporated at temperatures ient to operate at atmospheric pressure. from 135 to 235 C. at a pressure of 27 mbar for about The residence time for the re-arrangement reaction 6 hours The concentrate 11 5 m 16 whic may be for instance from 1 to 72 hours preferably from 958% by weight H 2804 gd g s z to 1; 33: 3 g; 3 to 24 hours 98% of the starting catalyst.

The re-arrangement react1on can be carried out in any suitable manner, for example, batchwise or continuously. Example 2 It is preferred to operate in a continuous manner.

The rearrangement reaction Product is y at A carbonylation reaction was carried out by feeding a least in part e.g. 30 to 70% wt./wt., to the carbonylat on mixture f TMS (91% by Weight) in aqueous 95% by reaction, after dilution with water if necessary to bring Weight H2304 and a Solution of DMO (36% by weight) the Sulphuric acid eeneentratioh to value In the -h in tetrachloroethylene separately at 45.7 and 57.6 ml./h. 90% to by Welght- The remelhdel' of the react1on respectively (4.17 moles H SO /mole DMO) to a stirred Product 1f any can he treated for the recovery of TMS 25 (1,300 rpm.) magnedrive autoclave charged with 391 g. by diluting the sulphuric acid to a concentration of below f 95% by weight H 80 and 39 g. of TMS under a pres- 80% by Weight preferably about 60% by Weig to cause sure of carbon monoxide (69 bar) at a temperature of the TMS to form a seParate hqhld Phase Whleh can h 20.5 to 23 C. over a period of 24.5 hours. After 6 hours he decanted; h Porhoh of the rearrangement react1on reaction product was continuously withdrawn (104.6 ml./ pl'ehlet Whleh 15 to he treated for the r y of TMS hr.) from the bottom of the autoclave and was continuis suitably combined with the carbonylation react1on prodously quenched with Water (23 to give 91% by after the latter h been treated to e e weight H 80 with respect to the water content and this and an of the TMS 15 then recovered by dhuhoh Wlth liberated TMO as a separate phase. After separation of waterthe TMO the catalyst raffinate was quenched again with The lnfehtloh 13 further desenbed Wlth reference to water (20 ml./hr.) and the precipitated TMS was sepathe followms examples rated by filtration. The TMO (2.96 mole) and TMS 0.22

mole) make corresponded to a selectivity to carboxyl Example 1 groups of 85.4% on the DMO used (3.98 mole).

A carbonylation reaction was carried out by feeding 4O gifi i sga g g i g fl fi gi zg g E g}: a F of TMS (9'4% Weight) m aqueous 95% by TMO) and allowing the mixtr ire to stand for M hours Welght H2804 and a Solution of DMO (36? by i i at ambient temperatures. Approximately half the reactemfhkmethylene separately at an tion mixture was then used to catalyse the carbonylation respectlvely (E16 mole? H2SO4/mole DMO) surfed step and the other half was diluted with water to give (1,300 r.p.m.) magnedrive autoclave charged with 95% 90% by weight H2504. The liberated TMO phase was by Welght H2804 (632 and TMS under a Presdecanted before diluting further to 67% by weight H 50 sure of carbon monoxlde bar) at a temperature of to precipitate the TMS. The unconverted TMO (22.8%) 185 to 21's, over a Pe.nod of 18 2 was recycled to the next rearrangement step. After washproduct was continuously Wlthdrawn (124 m 3) mm ing and drying the TMS obtained corresponded to 94% sethe bottom of the autoclave and was continuously 50 1 ctivit on th TMO consumed quenched with water (3.5 ml./h.) to give 91% by weight 6 y e H wtih respect to water content and this liberated Example 3 TMO as a separate phase. After separation of the TMO the catalyst raflinate was quenched again with water (33.6 A process was carried out as in Example APProxi. mlfh.) and the precipitated TMS was separated by fil- 55 mately by Weight of the rearrangement reaction tratlon' The TMO (2'003 9. and TMS (0339 mole} product was fed to the carbonylation reaction so that for g g sgi gfigi z 1 2:2333 to carboxyl groups 0 every mole of DMO fed (dissolved in 2 moles tetrachloro- A rearrangement reaction was then carried out by mixethylene), 8 9 moles of sulphunc con ing the TMO with 99% by weight H SO (10,3 m l 60 taming the product of rearran g1ng 0.68 mole of TMO H SO /mole TMO) and was stood for 24 hours at amgiven in the table. as h y 301d y were e bient temperature. Approximately half th r a ti ixto the carbonylation react1on. The carbonylation conditure was then used to catalyse the carbonylation step and tions used and the results obtained are shown m Table 1.

TABLE 1 Reagents molar ratio Reaction cggbexsytfic H2804 h s Presshlrih Tern Residence lia lhhf W953i DMO Solvent re cg z le (p.s.i.g?) 0?) time (11.) TMS TMO tivity I 1 In carbonylation product per 100 moles of DMO used. 3 of conversion of DMO to carboxylic acids groups.

3,776,951 6 Example 4 of the sulphuric acid feed rearrangement reaction product containing 2,2,7,7-tetramethyl suberic acid and concenggggs fi gghg a gg s g: ig fgz gg i gig: trated sulphuric acid, after dilution with water if necessary tion product was fed to the carbonylation reaction so that to glve a Shlphhnc ac1d cohcehtrahoh m the rahge 90 t for every mole of DMO fed (dissolved in 1-5 moles of 5 by Weight and recohermg h shhenc tetrachloroethylene) 4.2 moles of 95% wt./wt. sulphuric ac1d from the carbonylatlon macho Productid containing the product f rearranging 7 mole 2. The process according to claim 1 wherein the 2,7-diof TMO, were fed to th carbonylafion ti Th methyloctene-4 is fed to the car-bonylat1on reactlon in solubonylation conditions used and the results obtained are [1011 in a Chlorinated hydrocarbon Solventshown in Table 2. 3. The process according to claim 1 wherein the con- TABLE 2 Reagents molar ratio Reaction Moles oi carboxyho H2804 Carbox- Pressure acids 1 Percent Dur (95% ylic acid bar Temp. Residence selec- (h.) w./w.) DMO Solvent recycle (p.s.i.g.) 0.) time (h.) TMS TMO tivity 1 I In carbonylation product per 100 moles of DMO used. 9 Of converslon of DMO to carboxylic acids groups.

Example 5 centration of the sulphuric acid fed to the carbonylation Comparative batchwise production of TMS according i i}? Zohe 1S z h 5% i to Belgian Pat. 735,340 and B. P. 1,270,939.A mixture e mg c 1 W 6 of 2.7-dimethyloctene-4 (1 mole) and tetrachloroethylene gh igl figzgggzigg33 h:$32 of Sulphhnc 1 mare entertains;martinis w 4 e an applied Pressure of 515 pisigi (355 bar) of carbon phuric ac1d required for the carbonylatlon reaction is obmonoxide over 4 hours at 19 to 29 C. The reaction tamed by hashing-from 30% to 75% Wh/wt' the reproduct was then mixed with ice to dilute the catalyst to arrangement reaction product to the carbonylation reaction. easements? is: a a The g a 1 prised TMS 0.392 mole) and TMO (0.176) mole). who p 6 n e e W hm reaction zone is from 3 :1 to 9: 1.

5 6 l i ihlxed fi 9 7. The process according to claim 1 wherein the car- 4 mo es) a emhera he ah e bonylation reaction is carried out at a temperature in the ture was stood for 24 h., diluted to give 90% w./w. H 80 o o range 0 to 100 C.

and h hherathd h L .2 molel) was sepa- 8 The process according to claim 7 wherein the carrate y extraction wit cyc o exane. e cata yst rafiinate was then diluted to 67% WJW. H2304 with Water and the bonylat1on reaction is carried out at a temperature in the ran 15t 35 C. flrcclpltated TMS (0063 mole) was Separated by hhra' 9h The phocess according to claim 1 wherein the car- The total TMS produced (0.455 mole) required the use igg gigg fgi 1S earned out at a pressure from 10 to g? 6 h g g 10. The process according to claim 1 wherein the con- 0 es were use 1h e cahohy a 10h S centration of sulphuric acid in the rearrangement reaction A similar mass balance on Example 1 gives a usage of is from 97% to 99% by weight. {holes Hzsodmhe of TMS of Whlch moles were 11. The process according to claim 1 wherein the amount used in the carbonylation step.

a of sulphuric acid in the rearrangement reaction is in the A further mass balance check on Example 2 shows that 2 19.7 moles H SO /mole of TMS were used of which 12.8 22 5 8 to 18 moles per mole of mmethyl octane: moles i s m the g gi step 12. The process according to claim 1 wherein the temh e a ove champ i S 0W at the hfle phochss perature in the rearrangement reaction is from 15 to requires less catalyst per unit production of TMS especial- 40:: C 1y at the carbonylation step where the capital cost of the 13. The process according to claim 1 wherein a part of g g hlgh pressure reactor cah be correspohdlhgly the rearrangement reaction product is combined with the re uce carbonylation reaction product after this has been treated We clalm' to recover the 2,2,7-trimethyl octanoic acid and the com- T phoceshfor prhduchoh 22774etrhmethy1 bined products treated to recover the 2,2,7,7-tetramethy1 subenc ac1d which compnses continuously feeding 2,7- suberic acid dimethyloctene-4, carbon monoxide, and aqueous sul- References Cited phuric acid having a concentration in the range 90 to 97% by weight to a carbonylation reaction zone to produce 2,2, UNITED STATES PATENTS 7-trimethyl octanoic acid, continuously separating the 2,2, 3,703,549 11/1972 Yeo an 260-53 3 A 7-trimethyl octanoic acid from the carbonylation reaction product, feeding the 2,2,7-trimethyl octanoic acid into JAMES A. PATTEN, Primary Examiner contact with sulphuric acid having a concentration in the D KELLY Assistant Examiner range 94 to 99.5% by weight in a rearrangement reaction to produce 2,2,7,7-tetramethy1 suben'c acid, continuously Us, (31, X R,

feeding to the carbonylation reaction zone as part or all 260537 P 

